What is the antonym for 'a deep wound'? 'A shallow wound'? Google offers only several hundred matches (whether singular or plural) which suggests it's not a common collocation.
There is the noun flesh wound:
: an injury involving penetration of the body musculature without damage to bones or internal organs
Generally, you hear this in the context of movies, TV shows, and other fiction where somebody gets shot, and it's used in the following type of dialogue, normally collocated with just:
"Are you okay?"
"Yes, I'm fine. It's just a flesh wound."
Google Books Ngram Viewer shows that this is much more common than other descriptive terms such as shallow, superficial, surface, or minor.
An antonym of "deep" in that context might be "superficial", so
A superficial wound
- Of, affecting, or being on or near the surface: a superficial wound.
You could also say
I think "a shallow wound" works, too.
In fact, I tried google search on "a shallow wound" and got almost 65,000 hits. It appears frequently at google books search too.